Various damages to materials are often resulted from, for example, corrosion, abrasion, oxidation, fatigue rupture and the like on the surface of the materials. The structure and characteristics of surface materials have a significant influence on the comprehensive performance of the materials. The preparation of a nanostructured surface with a certain thickness on the surface of materials may improve the overall mechanical property and service behavior in various environments of the materials. There are three major ways of acquiring a nanostructured surface on a metal surface: surface coating or deposition, surface self-nanocrystallization and hybrid nanocrystallization.
Surface coating or deposition: the prepared particles in nanometer are solidified on a surface of materials so that a nanostructured surface with identical or different chemical components is formed on the surface of the substrate materials. At present, the common coating and deposition methods include Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), sputtering, electroplating, electrolytic deposition, etc. The key point of such technologies is to achieve firm combination between nanoparticles on the surface and a substrate. Patent Application CN100362128C, filed by Donghua University and entitled “Method and Apparatus for Depositing Nanoparticle Film by Atmosphere Flat Discharge CVD”, employed an atmosphere flat discharge method to uniformly deposit a nanoparticle film with identical components and a certain crystallization characteristic on surfaces of various materials. However, this method has disadvantages of high temperature of the substrate materials, low deposition rate, difficult local deposition on the substrate materials, and the generation of harmful gas during the deposition. Patent Application CN101298677, filed by Jilin University and entitled “Preparation of Wear-resistant and Corrosion-resistant Nano-composite Plating Layer on Magnesium Alloy Surface”, prepared a nano-composite plating layer on a magnesium alloy surface by placing a chemically-plated magnesium alloy sample into nano-composite plating solution and then performing electrodeposition nano-composite plating. However, the plating layer has a non-uniform thickness, the technological process is relatively complicated, and the preparation of multiple kinds of chemical solution is required and thus the process is not clean enough.
For conventional laser shock, an intense laser beam with high power density and short pulse is employed to shock a metal surface, and the coating on the metal surface absorbs the laser energy to result in vaporization, ionization and expanding explosion and then forms a plasma shock wave transmitting to the metal inside. However, the shock force generated by a general process is insufficient to embed nanoparticles into the metal surface.